The present invention is concerned with a tool element. More specifically, the present invention is concerned with a moulding tool or an element for a moulding tool having temperature control for moulding large, slow-to-cure workpieces.
As discussed in the applicant's prior published international patent application, WO2011/048365, it is known to provide a tool having a plurality of zones which are independently controlled in order to achieve the desired properties of the resulting moulded workpiece.
Known mould tools having temperature control are required to be dynamic—that is to increase and decrease the temperature of the tool as quickly as possible to respond to the tool control system (which may monitor the properties of the workpiece material). Being dynamic means that the tools can more accurately control the curing process.
Such systems require a source of pressurised fluid either from a pressurised tank or a compressor. Provision of a pressurised fluid allows an increased amount of energy to be transferred to and from the tool (depending on whether the user is heating or cooling the tool surface). In addition, the increased fluid velocity that compressed or pressurised cooling air provides increases the heat transfer coefficient between the fluid and the tool control surface. In certain applications, responsiveness is not a key factor in moulding. For example, when large thick structures such as wind turbine blades are moulded, curing occurs over a long period of time and is generally predictable. Tools for moulding articles of this nature do not need to be dynamic as the overall curing time is far longer than the heating or cooling time. Under these circumstances, efficiency is more important.
A further problem with the prior art is that compressed air lines need to be router throughout the mould tool. This is costly and complex. It is an object of the present invention to provide a tool element temperature control system which is better suited to large, slow curing workpieces.